Heretofore liquid soap dispensers have been known. For example, see U.S. Pat. Nos. 4,349,133; 4,546,904; 4,667,854; and 4,463,876. These dispensers, however, have complex check valve mechanisms which are expensive to manufacture and difficult to maintain. These drawbacks increase the cost of the dispenser and reduce the dispenser's reliability.
U.S. Pat. No. 4,349,133 discloses a liquid dispenser and refill package. The dispenser has a housing, a flexible plastic pouch, a pumping mechanism, and a check valve mechanism. The housing has a front half and a rear half which are joined together by a hinge. A pouch is supported within and removable from the housing. The pouch includes a reservoir and a tubular pumping section in fluid communication with the reservoir. A "duck bill" check valve for preventing liquid leakage from the pumping section is located at the free end of the pumping section of the pouch. In FIG. 6 of U.S. Pat. No. 4,349,133, the "duck bill" check valve is illustrated. The "duck bill" valve is a plastic cylindrical closure having a diametric slit thereacross which is normally closed but openable when the liquid is pressurized by the pump. The pumping mechanism is contained within the housing and operates on the pumping section of the pouch. The pumping mechanism comprises a first block and a second block which sandwich the pumping section and squeeze the pumping section when forced together. The second block is mounted on a lever hinged to the housing. The lever actuates the pumping mechanism when grasped and pulled forward.
U.S. Pat. No. 4,546,904 is directed to a dispenser and a package for liquid which is similar to the dispenser described in U.S. Patent No. 4,349,133. The check valve of this patent has two embodiments: the first is a ball and spring valve (FIG. 5); the second, a slit diaphragm valve (FIG. 4).
U.S. Pat. No. 4,667,854 is directed to a liquid dispenser similar to those discussed above, except the pumping mechanism includes a roller which travels along the length of the pumping section, thereby squeezing liquid out of the pumping section. The check valve (FIGS. 5 and 6) comprises a nozzle which has a small opening. The small opening combined with the surface tension of the liquid apparently prevents leakage from the pouch.
U.S. Pat. No. 4,463,876 discloses a liquid dispenser that has a pouch (See FIGS. 1 and 5). The pouch has a reservoir section, a pumping or metering section, and a discharge nozzle. A resilient plate attached to the front half of the housing compresses the pumping section of the pouch when the housing adjacent the plate is pushed.
With regard to liquid storage pouches, U.S. Pat. Nos. 3,610,477, 3,825,157 and 4,252,257 are deemed relevant to the check valve mechanisms in general, even though not specifically adapted for use in dispensers. U.S. Pat. Nos. 3,825,157 and 4,252,257 are cumulative of U.S. Pat. No. 3,610,477 and accordingly are not discussed.
U.S. Pat. No. 3,610,477 discloses a pouch having a nozzle that has a "lateral bow". The term "lateral" apparently means from the top layer to the bottom layer of the pouch and not from side-to-side of the pouch. The "bow" is best illustrated in FIG. 1A. The lateral bow of the top and bottom layers apparently cause them to bear against one another and thereby close the nozzle.
Additionally, note FIGS. 2A, 2B and 3 which illustrate "dimples".
The foregoing liquid dispensing systems and pouches are unnecessarily complex in structure and in operation, and, therefore, are difficult and expensive to manufacture and difficult to maintain.